3) Now this one was made possible thanks to Merranvo; it's a door that will only open from one side. It's a complex door, and need the use of a second entity to work. (I use triggerzone). Now what you do is apply this code to your door,

Now, at this point it'll never work. You'll have to put in the door's property ifused, the name of your second entity, or zone. Then, for your second entity or zone, you'll put in the ifused field the name of your door. Note that you should use unique names! The main idea is that both entities are linked together.
But it appears it wouldn't work with enemies, because they activate everything in their way to move, so the activations would get mixed up.

I know that some script might turn wierd with some enemies playing to much around doors, but I gess it's a good start for somebody that is using FPSC for 10 days !

To flashing snall and others, the difference between colons and commas, is for separating multiple actions/conditions this way:

Every line of correct code in fpi start this way:Maybe it's used only to separate lines without using the enter key, but I don't really know.

Now, the second ":" separates the condition(s) to the action(s), and you can't have scripts in fpi with only action(s) or only condition(s):condition(s):action(s)

If you have more than one conditions or actions on your line of code, you will separate every conditions with "," and every actions with ",". But don't forget the ":" between the last condition and the first action! :condition1, condition2,condition3...:action1,action2,action3...

So it's about it... And there is an example of what you should have, I put the text in bold as something you MUST have in your line:

:condition1,conditionX:action1,actionX

So it's not too hard to understand, but if you still need help, maybe you should try FPI MAKER, it's an app. developped to code your fpi and your code is even separated with colors so you can easily see what you do as actions and conditions, which are separated in blue, or red.

I had the link for the site to get FPI MAKER, but it seems broken...
Anyway, if you need it, I could upload it here, but I think I don't have the rights to do that? But if you need it and think it's OK, then I'll do upload it there.